The present invention relates to equipment for the manufacture of construction materials and more particularly it relates to devices for heat-treatment of free-flowing materials.
For example, the device can be utilized for removal of chlorides from cement clinker when the latter is being calcinated with chlorine-containing compounds, and for its subsequent cooling.
A rotary shaft kiln is known for calcination of small-lump materials, e.g. strong ceramic pellets comprising low-temperature and high-temperature chambers with gas-permeable walls made in the form of inclined shutters, and an inclined bottom.
The formed pellets enter the low-temperature calcination chamber wherein they are heated in the lower part of the chamber by the heat transferred from the combustion products discharged from the furnace and penetrating through the shutter walls, whereupon the calcined pellets enter the high-temperature calcination chamber. From here the finally-calcined pellets fall on a movable horizontal conveying grate where they are cooled and transferred for storage.
A disadvantage of the shaft kiln for calcination of small-lump material lies in that it has no means for disintegrating the material to the required granulometric composition, and in that there is a risk of hanging-up of the material. Moreover, the device fails to provide uniform distribution of the combustion products over the entire height of the shaft and cannot remove chlorides from the material which impairs the quality of the product.